Developmental morphology of the cervical vertebrae and the emergence of sexual dimorphism in size and shape: A computed tomography study

The reliability of a modified three-stage cervical vertebrae maturation method for estimating skeletal growth in males and females

BACKGROUND

Reliability of the six-stage cervical vertebrae maturation method to evaluate skeletal growth was evaluated on the combined male and female samples and revealed diverse results. The current study aimed to determine the reliability of the modified three-stage cervical vertebrae maturation method for estimating the skeletal growth of males and females.

METHODS

Pretreatment lateral cephalometric radiographs of 137 orthodontic patients were utilized to evaluate the intra- and inter-observer reliability of a modified cervical vertebrae maturation method. Four independent examiners categorized each radiograph into one of the three skeletal growth stages according to the cervical vertebrae morphology: (1) a pre-peak group (combining the CS1 and CS2 stages), (2) a peak group (combining the CS3 and CS4 stages), and (3) a post-peak group (combining the CS5 and CS6 stages). The Kappa index and the Fleiss multirater Kappa test were carried out to determine the reproducibility of this method.

RESULTS

The studied sample included cephalometric radiographs of 68 males (49.6%) and 69 females (50.4%) aged between 7 and 58 years; no significant age difference was found between the sexes (p = 0.189). The overall inter-observer reliability was 0.689 (p < 0.001), and the inter-observer reliability for the post-peak stage showed only Kappa = 0.896 (p < 0.001). The Kappa values were significantly greater in males than in females during the peak stage (0.626 and 0.488, respectively).

CONCLUSIONS

A modified three-stage cervical vertebrae maturation method showed substantial overall inter-examiner agreement; however, differential reliability for diverse skeletal maturation stages and sexes was found.

Development of a spinopelvic complex finite element model for quantitative analysis of the biomechanical response of patients with degenerative spondylolisthesis

Research on degenerative spondylolisthesis (DS) has focused primarily on the biomechanical responses of pathological segments, with few studies involving muscle modelling in simulated analysis, leading to an emphasis on the back muscles in physical therapy, neglecting the ventral muscles. The purpose of this study was to quantitatively analyse the biomechanical response of the spinopelvic complex and surrounding muscle groups in DS patients using integrative modelling. The findings may aid in the development of more comprehensive rehabilitation strategies for DS patients. Two new finite element spinopelvic complex models with detailed muscles for normal spine and DS spine (L4 forwards slippage) modelling were established and validated at multiple levels. Then, the spinopelvic position parameters including peak stress of the lumbar isthmic-cortical bone, intervertebral discs, and facet joints; peak strain of the ligaments; peak force of the muscles; and percentage difference in the range of motion were analysed and compared under flexion-extension (F-E), lateral bending (LB), and axial rotation (AR) loading conditions between the two models. Compared with the normal spine model, the DS spine model exhibited greater stress and strain in adjacent biological tissues. Stress at the L4/5 disc and facet joints under AR and LB conditions was approximately 6.6 times greater in the DS spine model than in the normal model, the posterior longitudinal ligament peak strain in the normal model was 1/10 of that in the DS model, and more high-stress areas were found in the DS model, with stress notably transferring forwards. Additionally, compared with the normal spine model, the DS model exhibited greater muscle tensile forces in the lumbosacral muscle groups during F-E and LB motions. The psoas muscle in the DS model was subjected to 23.2% greater tensile force than that in the normal model. These findings indicated that L4 anterior slippage and changes in lumbosacral-pelvic alignment affect the biomechanical response of muscles. In summary, the present work demonstrated a certain level of accuracy and validity of our models as well as the differences between the models. Alterations in spondylolisthesis and the accompanying overall imbalance in the spinopelvic complex result in increased loading response levels of the functional spinal units in DS patients, creating a vicious cycle that exacerbates the imbalance in the lumbosacral region. Therefore, clinicians are encouraged to propose specific exercises for the ventral muscles, such as the psoas group, to address spinopelvic imbalance and halt the progression of DS.

Digital anatomical features of morphological development in the atlantoaxial synchondroses in children aged 1 to 6 years old: a retrospective study of CT images

OBJECTIVE

To investigate the anatomical indexes and anatomical positional indexes of the atlantoaxial synchondroses in normal Chinese Han children aged 1-6 years, and to analyze the changing law of the atlantoaxial cartilage union with the growth and development of age and its influence on the atlantoaxial ossification in children.

METHODS

A retrospective collection of CT imaging of 160 cases of normal cervical spine in children aged 1 to 6 years old was conducted. The cases were divided into six age groups, with each group representing a one-year age range. Measure the morphological anatomical indicators and anatomical positional indicators of the atlantoaxial synchondroses. Record and statistically analyze the measurements of each indicator.

RESULTS

Measurements were taken on various parameters of the atlantoaxial synchondroses. TD, SD, height, area, and perimeter all gradually decreased among the groups. Distance between bilateral atlantal anterolateral synchondroses increased gradually from Group A to Group F, while the angle formed along the long axis in the cross-section showed a decreasing trend. Distance between the axoid dentolateral synchondroses and between the neurocentral synchondroses increased gradually from Group A to Group F, with the angle value in the cross-section showing a gradual decrease, and distance from the odontoid apex increasing from Group A to Group F.

CONCLUSIONS

The atlantoaxial synchondroses gradually decrease in size with age, and ossification levels increase with age, with faster ossification occurring during a 1-2 years-old period. The anterolateral synchondroses, dentolateral synchondroses, and neurocentral synchondroses all gradually ossify towards the lateral direction with increasing age.

Evaluation of the usage of the cervical 7th vertebra in sex estimation with measurements on computerized tomography images

Sex estimation is the primary step in biological profiling via identification using skeletal elements. The aim of the present study was to evaluate the usefulness of the seventh cervical vertebra for sex estimation. The cervical computed tomography scans of 200 female and 200 male patients aged ≥ 20 years were analyzed. Eight different measurements of the seventh cervical vertebra were performed, including the transverse and anteroposterior diameters of the foramen vertebra, transverse and anteroposterior diameters of the corpus vertebra inferior surface, height of the corpus vertebra, corpus vertebrae-spinous process angle, and height and length of the spinous process. Independent two-sample t-test was performed; significant differences were observed between the sexes in all measurements except corpus vertebrae-spinous process angle. Further, univariate logistic regression analyses revealed that the length of spinous process showed the highest dimorphism. Among the univariate models created, the model obtained using only the length of the spinous process reached an accuracy rate of 80 %. Multivariate logistic regression analysis (via Forward LR Wald) was used for sex estimation with an accuracy of up to 90.8 % (89 % for men and 92.5 % for women). In conclusion, the seventh cervical vertebra is dimorphic in the Turkish population and allows sex estimation with high accuracy rates.

Ontogeny of morphological variations in the vertebral column: Prevalence and bony variability in young Spanish children

Pre- and postnatal development and variability in discrete vertebral traits have been poorly described in embryonic studies. Numerous authors have reported that these variations are observable only from adolescence; scientific publications on the vertebrae of fetuses and infants are scarce. Thus, the aims of this study were to (1) describe the ontogeny and variability of anatomical variations in the vertebral column of a Spanish infant population and (2) analyze the frequency and relationship between sex, age, and intertrait variables. A total of 4728 vertebrae from 197 skeletons were studied. The age at death ranged from 22 intrauterine weeks to 8 years. Twenty morphological traits related to vertebral column development were analyzed. A descriptive statistical analysis was performed, and the chi-square test was used to measure the relationship between sex, age, and intertrait variables. We observed that 88.32% of skeletons expressed discrete traits along the spine. In fetuses, the double transverse foramen and unclosed transverse process of the axis were the most prevalent traits. In infants older than one year, the appearance of the L5 cleft neural arch, unclosed transverse process of the atlas, and craniocaudal shifts were frequent. A significant result was found between sex and the unclosed transverse process in the axis. The intertrait relationship was significant for all traits that shared the same embryonic structure. Morphological variations became visible following the appearance of ossification centers during the pre- and postnatal periods, and their etiology was associated with embryonic development.

Growth and sexual dimorphism of the hyoid bone and its relationship to the mandible from birth to 19 years: A three-dimensional computed tomography study

The hyoid bone and the hyomandibular complex subserve the functions of respiration, deglutition, and speech. This study quantified the growth of the hyoid bone and the hyomandibular relationships in males and females from birth to 19 years. Using 97 computed tomography (CT) scans, from a previous study (Kelly et al., 2017) on mandibular growth from 49 individuals (16 with longitudinal scans), landmarks were placed on 3D CT models and used to calculate four distance, and three angular measurements. A general increase in growth trend was observed in hyoid bone linear measurements-length, width, and depth-as well as relational mandible-to-hyoid distance, throughout the developmental ages examined in both males and females, with most variables having larger measurements for females up to age 10 years. A general decrease in all three angular measurements was observed in both males and females up to approximately age 12 years, at which time male angular measurements gradually increased with significant sexual dimorphism emerging after age 15 years. As expected, postpubertal males had greater hyoid angle than females; they also had greater hyoid angle of inclination than mandible body inclination (with inclination relative to the anterior-posterior nasal plane), likely related to hyo-laryngeal descent. This study contributes to normative data on hyoid bone and hyomandibular relational growth in typically developing individuals and provides a baseline against which structural and functional influences on anatomic growth may be examined by clinical disciplines that address the aerodigestive and speech functions, as well as the fields of anatomy, forensics, and anthropology.